Electronic thermostat

ABSTRACT

An electronic thermostat apparatus for controlling a temperature of a coolant of an engine in a vehicle may include a housing connected to a plurality of flow paths through which the coolant of the engine flows, a wax case installed inside the housing and provided with a wax accommodation space therein, a glow plug heater inserted in a wax filled inside the wax accommodation space and configured to generate heat by receiving an external power, a driving body engaged to the wax case and moving according to deformation of the wax by the heat of the glow plug heater, a main valve engaged to the driving body and configured to open/close a radiator-side flow path by a movement of the driving body, and an elastic member elastically biasing the main valve to the radiator-side flow path.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority to Korean Patent Application No. 10-2012-0036932 filed on Apr. 9, 2012, the entire contents of which is incorporated herein for all purposes by this reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an electronic thermostat, and more particularly, to an electronic thermostat capable of rapidly reaching a target temperature by employing a glow plug type heater.

2. Description of Related Art

In general, a thermostat for a vehicle is installed between an engine and a radiator, and is automatically opened/closed according to a change in a temperature of a coolant to adjust a flow rate flowing toward the engine, thus serving to maintain an appropriate temperature of the coolant.

Most of the thermostats for a vehicle in the related art are a mechanical thermostat having a structure in which power by expansion of wax is transferred to a piston to incur an open/close displacement of a valve.

However, the mechanical thermostat employs a method of operating according to an open/close temperature set as a specified temperature, that is, a method of simply opening/closing a valve only at a preset temperature. Accordingly, in consideration recent demands of implementing high performance and high efficiency of a vehicle, there is a limit in actively handling a change in a driving environment or other conditions of the vehicle.

An electronic thermostat employing a variable control method for maintaining a temperature of a coolant of an engine in an optimum state while complementing a drawback of the mechanical thermostat has been recently suggested.

The electronic thermostat controls the temperature of the coolant of the engine according to a driving environment, such as a load state of the vehicle and the like, so that it is possible to always maintain an optimum engine cooling state and expect effects of improving fuel efficiency and decreasing an exhaust gas compared to the mechanical thermostat.

FIG. 1 illustrates an example of the electronic thermostat. As illustrated in FIG. 1, the electronic thermostat generally has a structure in which wax 2 is accommodated in a pallet 1, a heat generation unit 3, such as a film resistant heater, is embedded at a front end thereof, and the heater generates heat through an external power supply plug to expand the wax and push a piston, so that a valve is operated.

In the electronic thermostat generating heat by using the film resistant heater and the like in the related art, it takes approximately 50 to 70 seconds to reach a target temperature of 300 to 350° C. It takes a great deal of time to reach the target temperature, so that there is a problem in that it is impossible to control a temperature of the coolant in real time and it is difficult to maximize an effect of improving fuel efficiency of a vehicle.

The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.

BRIEF SUMMARY

Various aspects of the present invention are directed to providing an electronic thermostat capable of controlling a temperature of a coolant in real time and maximizing an effect of improving fuel efficiency of a vehicle by improving a control response characteristic of the electronic thermostat.

In an aspect of the present invention, an electronic thermostat apparatus for controlling a temperature of a coolant of an engine in a vehicle, may include a housing connected to a plurality of flow paths through which the coolant of the engine flows, a wax case installed inside the housing and provided with a wax accommodation space therein, a glow plug heater inserted in a wax filled inside the wax accommodation space and configured to generate heat by receiving an external power, a driving body engaged to the wax case and moving according to deformation of the wax by the heat of the glow plug heater, a main valve engaged to the driving body and configured to open/close a radiator-side flow path by a movement of the driving body, and an elastic member elastically biasing the main valve to the radiator-side flow path.

The electronic thermostat apparatus may further include a bypass valve coupled to the driving body and configured to open/close a bypass flow path that does not circulate through a radiator while interworking with the main valve.

The electronic thermostat apparatus is installed at an inlet of the engine through which the coolant flows in the engine or an outlet of the engine through which the coolant is discharged from the engine.

The glow plug heater may include a cylindrical case, a heating tube coupled to one end of the case, a coil installed inside the heating tube, and an insulation member filled in a space between the coil and the heating tube.

The coil may include a heating coil configured to generate the heat or a temperature adjusting coil configured to control an increase in a temperature of the heating coil.

The insulation member is made of magnesium oxide (MgO) powder.

A transmission fluid is disposed between the wax and the driving body in a cylindrical element guide connected to the wax case.

A rubber moving body is disposed between the transmission fluid and the driving body.

An inner diameter of a cylindrical frame receiving the wax case is larger than an inner diameter of a cylindrical element guide slidably receiving the driving body.

In another aspect of the present invention, an electronic thermostat apparatus for cooling a temperature of a coolant of an engine in a vehicle may employ a glow plug heater that heats a wax.

The glow plug heater may include a cylindrical case, a heating tube coupled to one end of the case, a coil installed inside the heating tube, and an insulation member filled in a space between the coil and the heating tube.

The coil may include a heating coil configured to generate heat or a temperature adjusting coil configured to control an increase in a temperature of the heating coil.

The insulation member is made of magnesium oxide (MgO) powder.

A transmission fluid is disposed between the wax disposed in the cylindrical case and a driving body disposed in a cylindrical element guide connected to a wax case containing the wax.

A rubber moving body is disposed between the transmission fluid and the driving body.

An inner diameter of a frame receiving the wax case is larger than an inner diameter of the cylindrical element guide

According to the electronic thermostat according to the exemplary embodiment of the present invention, it is possible to minimize a time required to reach a target temperature by using the glow plug type heater. Accordingly, it is possible to control a temperature of a coolant in real time according to a driving condition of a vehicle.

Further, according to the present invention, a temperature of a coolant is controlled in real time, thereby maximally improving fuel efficiency of a vehicle.

The methods and apparatuses of the present invention have other features and advantages which will be apparent from or are set forth in more detail in the accompanying drawings, which are incorporated herein, and the following Detailed Description, which together serve to explain certain principles of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of an electronic thermostat in the related art.

FIG. 2 is a cross-sectional view of an electronic thermostat according to an exemplary embodiment of the present invention.

FIG. 3 is a cross-sectional view of a glow plug type heater according to an exemplary embodiment of the present invention.

FIG. 4 is a diagram schematically illustrating a coolant flow path at which an electronic thermostat of the present invention is installed.

FIG. 5 is a cross-sectional view of a coolant flow path at which an electronic thermostat of the present invention is installed

FIG. 6 is a perspective view of a coolant flow path at which an electronic thermostat of the present invention is installed.

It should be understood that the appended drawings are not necessarily to scale, presenting a somewhat simplified representation of various features illustrative of the basic principles of the invention. The specific design features of the present invention as disclosed herein, including, for example, specific dimensions, orientations, locations, and shapes will be determined in part by the particular intended application and use environment.

In the figures, reference numbers refer to the same or equivalent parts of the present invention throughout the several figures of the drawing.

DETAILED DESCRIPTION

Reference will now be made in detail to various embodiments of the present invention(s), examples of which are illustrated in the accompanying drawings and described below. While the invention(s) will be described in conjunction with exemplary embodiments, it will be understood that the present description is not intended to limit the invention(s) to those exemplary embodiments. On the contrary, the invention(s) is/are intended to cover not only the exemplary embodiments, but also various alternatives, modifications, equivalents and other embodiments, which may be included within the spirit and scope of the invention as defined by the appended claims.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2 is a cross-sectional view of an electronic thermostat 10 according to an exemplary embodiment of the present invention.

As illustrated in FIG. 2, the electronic thermostat 10 according to the exemplary embodiment of the present invention may include a housing 100, a wax case 200, a glow plug type heater 300, a driving body 400, a main valve 500, an elastic member 600, and a bypass valve 700.

The housing 100 is a part connected to a plurality of flow paths through which a coolant of an engine of a vehicle flows. As illustrated in FIGS. 4 to 6 as the exemplary embodiment, the housing 100 may be connected with a radiator-side flow path P1 through which the coolant flows in after circulating the radiator 20, a bypass flow path P2 through which the coolant directly circulates toward the water pump 30 of the engine 40 without circulating the radiator 20, and a water pump-side flow path P3 at an inlet through which the coolant flows in the engine 40.

A fixed part 110 is integrally formed inside the housing 100, so that the glow plug type heater 300 may be fixed.

A space for accommodating a connector 350 connecting the thermostat 10 to external power may be formed in the fixed part 110.

The wax case 200 is installed inside the housing 100, and has a wax accommodation space for filling the inside of the wax case 200 with the wax 210.

The wax case 200 may be installed under the fixed part 110 of the housing 100, and may have a through hole 220 formed inside thereof so that a heating tube 320 of the glow plug type heater 300 passes through the through hole 220 to be inserted in the wax accommodation space.

The glow plug type heater 300 is inserted in the wax 210 filled in the wax accommodation space of the wax case 200, and generates heat by receiving external power through the connector 350. The glow plug type heater 300 is electronically controlled under the control of an external controller, such as an electronic control unit (ECU).

In general, a glow plug is an apparatus used for a diesel engine and the like to pre-heat interior air so as to help ignition of fuel.

That is, the present invention is characterized in that the glow plug used for ignition of the diesel engine and the like is applied as the heater 300 of the thermostat 100, contrary to the related art.

FIG. 3 is a cross-sectional view of the glow plug type heater 300 according to an exemplary embodiment of the present invention.

As illustrated in FIG. 3, the glow plug type heater 300 according to the exemplary embodiment of the present invention may include a cylindrical case 310, a heating tube 320 coupled to one end of the case 310, a coil 330 installed inside the heating tube 320, and an insulation member 340 filled inside a space between the coil 330 and the heating tube 320.

The case 310 may be formed of a metal material, and may be coupled with the connector 350 connecting the external power at an upper portion thereof and coupled with the wax case 200 of the thermostat 10 at a lower portion thereof.

The heating tube 320 may be formed so that one end thereof is closed, and may be inserted inside the wax 210 filled inside the wax accommodation space. The heating tube 320 serves to increase a temperature of the wax 210 by using the heat generated from the coil 330 and prevent the coil 330 from being chemically corroded.

In one or multiple exemplary embodiments, as illustrated in FIG. 2, the heating tube 320 may be forcibly inserted and installed between an interior circumferential surface of the cylindrical case 310 and a core shaft 351 inserted from the connector 350 up to an inside of the case 310 to conduct electricity, and one end of the heating tube 320 may be formed in a curved surface by swanging.

Specifically, as illustrated in FIG. 3A, the coil 330 may include a heating coil 331 for generating heat by power applied from the outside and a temperature adjusting coil 332 for maintaining a uniform temperature by controlling temperature increase according to a change in inherent resistance according to an increase in a temperature of the heating coil 331.

One end of the heating coil 331 may be fixed to an interior circumferential surface of the heating tube 320 by welding, and the temperature adjusting coil 332 may be electrically connected to the core shaft 351.

In one or multiple exemplary embodiments, the heating coil 331 may be coupled to an interior circumferential surface B of the heating tube 320 by laser welding, and similarly, the temperature adjusting coil 332 may be fixed to one end A of the core shaft 351 by laser welding and electrically connected with the core shaft 351.

In the meantime, in another exemplary embodiment, the coil 330 may only include the heating coil 331 for generating heat by power applied from the outside as illustrated in FIG. 3B. In this case, in one or multiple exemplary embodiment, one end of the heating coil 331 may be coupled to the interior circumferential surface B of the heating tube 320 by laser welding and the other end of the heating coil may be coupled to the end A of the core shaft 351 by laser welding.

The insulation member 340 is filled inside the heating tube 320.

In one or multiple exemplary embodiments, the insulation member 340 may be magnesium oxide (MgO) powder. The magnesium oxide (MgO) powder, which is an insulator, serves to maintain insulation between the heating tube 320 and the coil 330, prevent movement of the coil 330, and transfer heat generated in the coil 330 to the heating tube 320.

In the meantime, the driving body 400 is disposed under the wax case 200 to be moved by deformation of the wax 210.

In one or multiple exemplary embodiments, as illustrated in FIG. 2, the driving body 400 is disposed inside a cylindrical element guide 410 coupled to one end of the wax case 200 to move. Further, a rubber moving body 440 may be disposed inside the element guide 410 and on the driving body 400, a transmission fluid 430 may be filled in an upper portion of the rubber moving body 440, and a diaphragm 420 may be formed between an upper surface of the transmission fluid 430 and the wax 210. Here, the transmission fluid 430 may be semifluid.

A space filled with the transmission fluid 430 inside the element guide 410 may include a slanted surface a diameter of which becomes gradually smaller as becoming closer from an upper portion at which the diaphragm 420 is installed to a lower portion. Accordingly, pressure of the transmission fluid 430 according to deformation of the diaphragm 420 may be concentrated to the rubber moving body 440, and the rubber moving body 440 pressurizes the driving body 400 disposed under the rubber moving body 440 with force of the concentrated pressure. Accordingly, through the aforementioned structure, the expansion pressure of the wax 210 may be transferred to the driving body 400 without loss, so that it is possible to accurately control flow of the coolant.

The main valve 500 performs a function of opening/closing the radiator-side flow path P1 by the movement of the driving body 400. The radiator-side flow path P1 is a flow path allowing the coolant discharged from the engine 40 to circulate through the radiator 20 and flow in the engine 40.

The elastic member 600 is disposed in a lower surface of the main valve 500 to perform a function of elastically supporting the main valve 500 to the radiator-side flow path P 1. Accordingly, when force is not applied from the outside, the main valve 500 closes the radiator-side flow path P1 by elastic force of the elastic member 600.

In the meantime, the bypass valve 700 opens/closes the bypass flow path P2 where the coolant does not circulate through the radiator 20 by interworking with the main valve 500. The bypass flow path P2 is a flow path allowing the coolant discharged from the engine 40 to directly flow in the water pump 30 of the engine without passing through the radiator 20. The bypass valve 700 may be disposed under the driving body 400 to be moved by pressure of the driving body 400.

In one or multiple exemplary embodiments, the main valve 500 and the bypass valve 700 may be connected through a frame 710 to be integrally formed as illustrated in FIG. 2. In this case, the bypass valve 700 and the main valve 50 move together by the pressure of the driving body 400.

In the meantime, the electronic thermostat 10 of the present invention including the aforementioned configuration may be installed at an inlet of the engine 40 through which the coolant flows in the engine 40 or an outlet of the engine 40 through which the coolant is discharged from the engine 40.

FIG. 4 is a diagram illustrating an exemplary embodiment in which the electronic thermostat 10 according to the exemplary embodiment of the present invention is installed at the inlet of the engine 40, FIG. 5 is a cross-sectional view in which the electronic thermostat 10 according to the exemplary embodiment of the present invention is connected to and installed at the coolant flow path, and FIG. 6 is a perspective view of a coolant flow path at which the electronic thermostat 10 according to the exemplary embodiment of the present invention is installed.

Hereinafter, an operation of the electronic thermostat 10 according to the exemplary embodiment of the present invention will be described with reference to FIGS. 2 to 6.

In a case where the coolant of the engine 40 is maintained at a set temperature, the main valve 500 closes the radiator-side flow path P1 by the elastic member 600 as illustrated in FIG. 2.

In this case, as illustrated in FIGS. 4 to 6, the coolant discharged from the engine 40 does not circulate through the radiator 20 and directly flows in the engine 40 through the water pump-side flow path P3 while passing through the bypass flow path P2.

In this situation, when a temperature of the coolant is increased by an operation of the engine 40 and thus becomes higher than the set temperature, the ECU instructs an operation of the glow plug type heater 300 in order to open the main valve 500. Accordingly, the external power is applied to the coil 300 through the connector 350, so that the temperature of the coil rapidly reaches the target temperature.

As the coil 330 of the glow plug type heater 300 generates heat, the wax 210 is expanded, and the diaphragm 420 that is in contact with the wax 210 receives pressure to be deformed. The pressure according to the deformation of the diaphragm 420 is transferred up to the driving body 400 by sequentially passing through the transmission fluid 430 and the rubber moving body 440. The driving body 400 moves down to apply pressure to the bypass valve 700, and thus the bypass valve 700 moves down.

The bypass valve 700 moves down to block the bypass flow path P2. Further, the main valve 500 integrally connected with the bypass valve 700 through the frame 710 simultaneously moves down to open the radiator-side flow path P1. Accordingly, as illustrated in FIG. 4, the coolant discharged from the engine 40 circulates through the radiator 20 through a flow path P1′ and then moves to the water pump-side flow path P3 through the radiator-side flow path P1 to flow in the engine 40. In this process, the coolant is heat-exchanged in the radiator 20, so that a temperature of the coolant is decreased.

When the temperature of the coolant becomes lower than the set temperature, the ECU recognizes the decrease of the temperature of the coolant and instructs to stop an operation of the glow plug type heater 300. Accordingly, the heat generation of the coil 330 is stopped and the expanded wax 210 is contracted, so that the driving body 400 moves up. Accordingly, the pressure of the driving body 400 pressing the bypass valve 700 disappears, so that the main valve 500 moves up by the elastic force of the elastic member 600 to close the radiator-side flow path P1, and the bypass valve 700 simultaneously moves up to open the bypass flow path P2.

Through the aforementioned process, the ECU electronically controls the thermostat 10, so that the temperature of the coolant may be uniformly maintained at a preset temperature.

Especially, according to an exemplary embodiment of the present invention, a temperature of the heater may rapidly reach a target temperature by employing the glow plug type heater 300, thereby rapidly and accurately controlling the temperature of the coolant. According to the comparison of the experimental results, in the related art employing the film resistant heater, it takes 50 to 70 seconds to reach a target temperature of 300 to 350° C., but in an exemplary embodiment of the present invention employing the glow plug type heater 300, it takes 30 seconds or shorter to reach a target temperature of 350° C., so that the present invention has a remarkably improved effect compared to the related art.

According to an exemplary embodiment of the present invention, the glow plug type heater 300 is applied to the electronic thermostat 10, so that it is possible to minimize a time required to increase a temperature of the coolant to a target temperature, and a heating amount of the glow plug type heater is electronically controlled through the pulse width modulation (PWM) control by the ECU, so that a characteristic of a cooling system may be diversified.

For convenience in explanation and accurate definition in the appended claims, the terms “upper”, “lower”, “inner” and “outer” are used to describe features of the exemplary embodiments with reference to the positions of such features as displayed in the figures.

The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teachings. The exemplary embodiments were chosen and described in order to explain certain principles of the invention and their practical application, to thereby enable others skilled in the art to make and utilize various exemplary embodiments of the present invention, as well as various alternatives and modifications thereof It is intended that the scope of the invention be defined by the Claims appended hereto and their equivalents. 

What is claimed is:
 1. An electronic thermostat apparatus for controlling a temperature of a coolant of an engine in a vehicle, the electronic thermostat apparatus comprising: a housing connected to a plurality of flow paths through which the coolant of the engine flows; a wax case installed inside the housing and provided with a wax accommodation space therein; a glow plug heater inserted in a wax filled inside the wax accommodation space and configured to generate heat by receiving an external power; a driving body engaged to the wax case and moving according to deformation of the wax by the heat of the glow plug heater; a main valve engaged to the driving body and configured to open/close a radiator-side flow path by a movement of the driving body; and an elastic member elastically biasing the main valve to the radiator-side flow path.
 2. The electronic thermostat apparatus of claim 1, further including: a bypass valve coupled to the driving body and configured to open/close a bypass flow path that does not circulate through a radiator while interworking with the main valve.
 3. The electronic thermostat apparatus of claim 1, wherein the electronic thermostat apparatus is installed at an inlet of the engine through which the coolant flows in the engine or an outlet of the engine through which the coolant is discharged from the engine.
 4. The electronic thermostat apparatus of claim 1, wherein the glow plug heater includes a cylindrical case, a heating tube coupled to one end of the case, a coil installed inside the heating tube, and an insulation member filled in a space between the coil and the heating tube.
 5. The electronic thermostat apparatus of claim 4, wherein the coil includes a heating coil configured to generate the heat or a temperature adjusting coil configured to control an increase in a temperature of the heating coil.
 6. The electronic thermostat apparatus of claim 4, wherein the insulation member is made of magnesium oxide (MgO) powder.
 7. The electronic thermostat apparatus of claim 1, wherein a transmission fluid is disposed between the wax and the driving body in a cylindrical element guide connected to the wax case.
 8. The electronic thermostat apparatus of claim 7, wherein a rubber moving body is disposed between the transmission fluid and the driving body.
 9. The electronic thermostat apparatus of claim 7, wherein an inner diameter of a cylindrical frame receiving the wax case is larger than an inner diameter of a cylindrical element guide slidably receiving the driving body.
 10. An electronic thermostat apparatus for cooling a temperature of a coolant of an engine in a vehicle, the electronic thermostat apparatus employing a glow plug heater that heats a wax.
 11. The electronic thermostat apparatus of claim 10, wherein the glow plug heater includes: a cylindrical case; a heating tube coupled to one end of the case; a coil installed inside the heating tube; and an insulation member filled in a space between the coil and the heating tube.
 12. The electronic thermostat apparatus of claim 11, wherein the coil includes a heating coil configured to generate heat or a temperature adjusting coil configured to control an increase in a temperature of the heating coil.
 13. The electronic thermostat apparatus of claim 11, wherein the insulation member is made of magnesium oxide (MgO) powder.
 14. The electronic thermostat apparatus of claim 11, wherein a transmission fluid is disposed between the wax disposed in the cylindrical case and a driving body disposed in a cylindrical element guide connected to a wax case containing the wax.
 15. The electronic thermostat apparatus of claim 14, wherein a rubber moving body is disposed between the transmission fluid and the driving body.
 16. The electronic thermostat apparatus of claim 14, wherein an inner diameter of a frame receiving the wax case is larger than an inner diameter of the cylindrical element guide 